PHY5 – Sub-THz Communications
Friday, 6 June 2025, 9:00-10:30, room 1.E
Session Chair: Thomas Kürner (Technische Universität Braunschweig, DE)
Joint AP and HMD Power Optimization of Sub-THz Virtual Reality Systems
Meng Li (IMEC, Belgium); Yigit Ertugrul (Imec, Belgium); Claude Desset (IMEC, Belgium); Sofie Pollin (KU Leuven, Belgium); Abdur Rahman Mohamed Ismail (University of Ghent, Belgium & IMEC, Belgium)
Virtual reality (VR) systems demand high throughput to enable high-quality video transmission. In the 6G subnetwork, the sub-THz is a potential candidate for the VR application. At those frequencies, the small wavelength of THz signals enables the realization of the integration of a larger number of antennas compared with mm-wave or low band frequency. How to optimize the power consumption for the access point (AP) and head–mounted displays (HMDs) in the sub-THz band has not yet been discussed. In this paper, a simulation environment has been developed to assess the power consumption of VR communication systems by considering a sub-THz multi–user MIMO system along with a dedicated power model. An optimization problem is written to jointly optimize the average power consumption of the AP and HMD, or either AP or HMDs individually, while meeting the throughput and BER requirements. We explore the trade-off between the complexity of the AP and HMDs, offering insights into system-level design choices for various VR user experiences, considering different video resolutions, compression schemes, antenna configurations, and bandwidth settings. Additionally, we investigated computational offloading from the HMD to the AP, providing a potential energy-saving solution for battery-constrained HMDs.
Evaluation of Switching Technologies for Reflective and Transmissive RISs at Sub-THz Frequencies
Sofia Inacio (INESC TEC, Portugal); Yihan Ma (University of Hertfordshire, United Kingdom (Great Britain)); Qi Luo (University of Herfordshire, United Kingdom (Great Britain)); Luca Lucci (CEA Leti, France); Awanish Kumar (CEA-LETI & University Grenoble Alpes, France); Jose Luis Gonzalez Jimenez (Université Grenoble-Alpes/CEA-Leti, France); Bruno Reig (CEA-LETI, France); Alexandre Siligaris (Cea, Leti, Minatec, France); Denis Mercier (CEA-Leti, France); Jonas Deuermeier and Asal Kiazadeh (NOVA University Lisbon, Portugal); Veronica Lain-Rubio (ACST, Germany); Oleg Cojocari (ACST GmbH, Germany); Tung Duy Phan and Ping Jack Soh (University of Oulu, Finland); Sergio Matos (ISCTE-IUL / Instituto de Telecommunicações, Portugal); George C. Alexandropoulos (University of Athens & University of Illinois Chicago, Greece); Luis M. Pessoa (INESC TEC & Faculty of Engineering, University of Porto, Portugal); Antonio Clemente (CEA-Leti, France)
For the upcoming 6G wireless networks, reconfigurable intelligent surfaces are an essential technology, enabling dynamic beamforming and signal manipulation in both reflective and transmissive modes. It is expected to utilize frequency bands in the millimeter-wave and THz, which presents unique opportunities but also significant challenges. The selection of switching technologies that can support high-frequency operation with minimal loss and high efficiency is particularly complex. In this work, we demonstrate the potential of advanced components such as Schottky diodes, memristor switches, liquid metal-based switches, phase change materials, and RF-SOI technology in RIS designs as an alternative to overcome limitations inherent in traditional technologies in D-band (110-170 GHz).
A Comparative Study on Phase Noise Model in Ultra-High Data-Rate Sub-THz Communications
Didem Aydogan (Sabanci University, Turkey); Korkut K Tokgöz (Sabanci University, Turkey & Evrim Co. Ltd., Japan); Mohaned Chraiti (Sabanci University, Turkey)
Phase noise and high Peak-to-Average Power Ratio (PAPR) are significant challenges for 6G communications over the sub-terahertz (sub-THz) band, affecting signal integrity and system reliability. While standardized PN models, such as those from Hexa-X and 3GPP, provide theoretical frameworks, their accuracy in real-world conditions remains uncertain, requiring hardware-specific tuning. This paper presents a comparative analysis of two PN models: a standardized Hexa-X model and a hardware-tuned 3GPP approach. The impact of PN on high-order modulation schemes is examined, revealing its influence on optimal subcarrier spacing and necessitating adjustments for high-order modulation, specifically in OFDM systems. The feasibility of DFT-s-OFDM for PAPR reduction under PN constraints is also investigated. Furthermore, PN mitigation via common phase error (CPE) estimation is evaluated, demonstrating distinct model-dependent performance variations. The findings provide critical insights into PN model selection and waveform optimization for robust 6G system design.
Statistics of the MFTR Fading Model with Applications to Wireless Communications Performance Analysis in High Frequency Bands
Maryam Olyaee (Telecommunication Research Institute (TELMA), Universidad de Málaga, Spain); Juan Manuel Romero-Jerez (University of Malaga, Spain)
The recently introduced Multi-Cluster Fluctuating Two-Ray (MFTR) fading model for wireless communications has been shown to provide an excellent fit to experimental measurements in the sub-THz band. The probability density function (PDF) and cumulative distribution function (CDF) of this model are given in terms of multifold generalized hypergeometric functions, series or integrals, which complicates further derivations. In this work, we derive a closed-form expression for the generalized moment-generating function (GMGF) of the signal-to-noise ratio (SNR) of MFTR fading, thus circumventing the complexity of this model, as it permits to obtain all the moments of the distributions and allowing for the rapid computation of a number of relevant performance metrics. The obtained statistical results are exemplified by analyzing wireless channels undergoing MFTR fading in terms of the symbol error rate (SER), the secrecy capacity outage in the presence of an eavesdropper, the exact and asymptotic outage probability under interference and the outage probability in a composite Inverse Gamma (IG) shadowing – MFTR fading model.
Frequency-Tunable RIS for Beam Split Mitigation in Wideband THz Massive MIMO Systems
Ibrahim Yildirim (McGill University, Canada & Koc University, Turkey); Tho Le-Ngoc (McGill University, Canada)
The beam split effect, caused by frequency-independent phase shifts in conventional hybrid beamforming, poses a significant challenge for wideband THz communication, undermining array gain and system performance. Despite the promise of THz frequencies for ultra-high data rates and abundant spectrum, their wideband nature exacerbates beamforming difficulties, necessitating innovative solutions to address these limitations. This paper introduces a novel frequency-tunable reconfigurable intelligent surface (FRIS) architecture that addresses beam split in angular-based hybrid beamforming THz systems. Drawing inspiration from graphene-based metasurfaces, the proposed FRIS is capable of shaping the propagation paths of different subcarriers independently, thereby ensuring consistent beam alignment over an ultra-wide bandwidth. Our design further leverages a reduced-complexity hybrid beamforming strategy at the transmitter, mitigating the hardware burden typically associated with fully digital solutions. Numerical evaluations reveal that the proposed architecture effectively mitigates beam split and achieves high spectral efficiency, providing a scalable and energy-efficient solution for future wideband THz communication systems.
